In the 1970s, the technique of percutaneous transluminal coronary angioplasty (PTCA) was developed for the treatment of atherosclerosis. Atherosclerosis is the build-up of fatty deposits or plaque on the inner walls of a patient's arteries; these lesions decrease the effective size of the vessel lumen and limit blood flow through the vessel, prospectively causing a myocardial infarction or heart attack if the lesions occur in coronary arteries that supply oxygenated blood to the heart muscles. In the angioplasty procedure, a guide wire is inserted into the femoral artery and is passed through the aorta into the diseased coronary artery. A catheter having a balloon attached to its distal end is advanced along the guided wire to a point where the sclerotic lesions limit blood flow through the coronary artery. The balloon is then inflated, compressing the lesions radially outward against the wall of the artery and substantially increasing the size of its internal lumen, to improve blood circulation through the artery.
Other procedures have subsequently been developed for the treatment of atherosclerosis. These procedures include applying an energy to a treatment site to break-up the fatty deposits or plaque on the inner walls of a patient's arteries. Such energies can include ultrasonic, microwave, radio frequency, cryogenic, optical laser, thermal, magnetic, pH, etc. Generally, in these procedures, a guide wire is inserted into the femoral artery and is passed through the aorta into the diseased coronary artery. A catheter having an energy transmission device attached to its distal end is advanced along the guided wire to a point where the sclerotic lesions limit blood flow through the coronary artery. Energy, directed from the energy transmission device, is applied to the inner walls of the artery breaking-up the fatty deposits or plaque. The removal of the fatty deposits or plaque subsequently increases the size of its internal lumen, to improve blood circulation through the artery. However, in many instances the accumulation of the fatty deposits or plaque is a recurring or chronic problem, requiring additional and recurring treatments.
In the 1980s, the technique of extracorporeal shockwave lithotripsy (ESWL) was developed for the management of renal and ureteral calculous disease. ESWL is a procedure in which renal and ureteral calculi (stones) are pulverized into smaller fragments by shockwaves. These small fragments then can pass spontaneously. This noninvasive approach allows patients to be rendered stone-free without surgical intervention or endoscopic procedures.
Traditionally, this was accomplished by placing the patient in a large water bath (e.g., the early-generation machine; Dornier HM3). In newer second-generation and third-generation devices, the large water bath has been changed to the use of small pools of water or water-filled cushions with a silicone membrane to provide air-free contact with the patient's skin. With the new designs, patients can be treated in a variety of positions to help in localization and to maximize the effect.
As these examples illustrate, therapeutic energy has been used for treatment purposes. Nevertheless, there remains a need for improved systems and methods for delivering, utilizing, and/or providing energy to a treatment site in a body.